1. Field of the Invention
The present invention relates to a rear bumper structure of a motor-powered surface vehicle.
2. Description of the Prior Art
Conventionally, motor vehicles are provided with front and rear bumper structures for absorbing shock loads which may be incurred by the vehicles in a crash. The rear bumper structure is usually made so that, as disclosed in Japanese laid-open patent publication No. Sho 61-27738, a skin plate having a channel-like cross section is connected to a vehicle body with an energy absorbing member made of polyurethane between the skin plate and the vehicle body. In an operation of a surface vehicle, an air flow is produced between the road surface and the vehicle body as shown in FIG. 11. The air flow is stirred up behind the vehicle body and, more specifically, just behind a rear bumper 130 of the vehicle, and becomes turbulent, which increases an air resistance of the vehicle body.
In an effort to decrease such air resistance, the Japanese utility model application Sho 57-153654, filed on Oct. 8, 1982 and disclosed for public inspection on Apr. 14, 1984 under disclosure No. Sho 59-57281, proposes to provide a rear bumper with apertures which may allow the air flow to pass through. It should, however, be noted that the structure proposed by the Japanese utility model would not be effective to decrease the air resistance to a satisactory extent because the apertures formed in the rear bumper structure might cause further turbulence.